Vodacom is not a loyal service provider...

Been with vodacom for I don't know how many years. But when I tried to upgrade they told me I don't have a good credit score but yet all my phone contracts have been with them. Today I called to cancel my contract they tell me January I will be paying because my notice it's not not a 30 days. How come when I pay them for everything they have ever billed me for without complains. I have had contract with vodacom since 2010 but today they treat me like they don't know me. How do they expect me to pay on the 15th January 2022 when I already paid on the 15 December 2021 for the airtime used. Mxm vodacom are ****s